Multi-interval switch actuator



P 1964 c. E. RILEY ETAL MULTI-INTERVAL SWITCH ACTUATOR 2 Sheets-Sheet 1 Filed May 10, 1962 FIG.I

Charles E Rlley Billy B.White,

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Sept. 22, 1964 c. E. RILEY ETAL MULTI-INTERVAL SWITCH ACTUATOR 2 Sheets-Sheet 2 Filed May 10, 1962 Charles E. Riley Billy B.Whi1e,

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United States Patent 3,149,495 MULTI-lNTERVAL SWITCH ACTUATOR Charles E. Riley, 2406 Stratford Road SE, Decatur, Ala, and hilly B. White, 3904 Pine Ave. SW., Huntsville, Ala. Filed May 10, 1962, Ser. No. 193,885 (Ilaims. (Cl. 74-54) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes Without the payment of any royalty thereon.

This invention relates to a multi-interval switch actuator and more particularly to a precision interval switch actuator utilizing a three speed cam principle.

In laboratories, test facilities, and automatic control systems for missiles there is a need for a precision switch actuator which can provide any number of desired time intervals. In the past interval switch actuators contained their own drive and clutch-brake system which provided a fixed time interval and could not be used in any other application. Electronic timers and mechanical preset timers provide substantially equal accuracy but their respective expense and size have been a decided disadvantage.

It is one object of this invention to provide an accurate interval switch actuator which can be installed in existing mechanical instruments or control systems without making any mechanical changes to the timer proper.

It is another object of this invention to provide an interval switch actuator with accuracy equal to that of electronic switch actuators but having a much lower cost.

It is a further object of this invention to provide an interval switch actuator with accuracy equal to that of mechanical preset switch actuators but not requiring as much utilization of space.

According to the present invention, the foregoing and other objects are attained by providing a mechanical switch actuator which utilizes a three speed cam principle to provide highly accurate time intervals. By varying the input speed to the switch actuator, the interval time may be increased or decreased.

Other objects and advantages of the invention will become apparent from a consideration of the following specification, taken together with the accompanying drawings, in which:

FIGURE 1 is an elevational view of the interval switch actuator partially shown in section.

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1.

FIGURE 3 shows a perspective view of the cam and gear assembly.

FIGURE 4 is a view taken along line 44 of FIG- URE 1.

Referring to FIGURE 1 numeral 2 designates an interval switch actuating assembly housed in a cylinder 4 having an open and a closed end. The frame of the switch actuating assembly includes an outer cylindrical plate 6, a central cylindrical plate 8 and an inner cylindrical plate it which are held together in spaced parallel relationship by three identical segmented studs 12, 14 and 16. Each stud is composed of three separate elements such as 16A, 16B and 16C. Element 16A has an internally threaded opening at one end and an externally threaded extension having a smaller diameter than the stud at the other end. Elements 16B and 16C are formed in the same manner but are of different lengths due to the spacing requirements between the cylindrical plates. Thus, the extension on element 16C extends through an opening in plate it) and is threadably engaged with the opening in element 168. The opening in plate 10 has a smaller diameter than the stud which bears against the side of plate in. The threaded extension of element ice 16B in turn extends through plate 8 and is threadably engaged with 16A. The threaded extension of element 16A is then threadably secured in a threaded opening in outer plate 6. Threaded screws 11, 13 and 15 extend through the closed end of cylinder 4 and threadably engage the respective openings in 12a), 14C and 16C to hold cylinder 4- in engagement with outer plate 6. Each of plates 8 and 1% has a cut-away portion on the periphery to provide space for a pivotal arm assembly. An arm 18 is pivotally mounted on a stud 22 within a yokeshaped housing 26 (see FIGURE 3). Housing 20 is suitably secured, as by screws, between plates 6 and 10. The pivot arm is actuated through a roller 5 attached at one end of the arm while the other end of arm 18 operates a micro-switch 7. An opening 23 is located at the center of the closed end of cylinder 4 allowing electrical leads from micro-switch 7 to be connected to any desired equipment.

Referring to FIGURE 2 an input drive shaft 24, which is driven by a clutch-brake system (not shown), extends through bearings 17 and 19 of plate 6 and bearing 21 of plate 8 and terminates between plates 8 and 10. Drive shaft 24 has a fine cam member 26 secured thereto and positioned near the center of the space between plates 6 and 8. A first sleeve 28 is freely mounted on the input drive shaft and is adapted to rotate at a slower s eed than shaft 24. A pair of gears 30, 32 are secured at each end of sleeve 28 and a medium cam member 25 is secured to gear 32 and is disposed adjacent one side of cam 26. A second sleeve 34 is freely mounted on shaft 24 and is adapted to rotate about shaft 24 at a slower speed than sleeve 28. A coarse cam member 27 is secured to one end of sleeve 34 and is disposed adjacent the other side of cam 26 while a gear 36 is secured to the other end of sleeve 34. A further gear 38 is directly secured to the end of shaft 24 and is positioned between plates 8 and It A first driven shaft 49, which is in axial alignment with shaft 24, has one end rotatably mounted in a bearing 42 of plate 6 while the other end extends through bearing 44 of plate 8 and terminates between plates 8 and 1G. Shaft 40 has a pair of gears 33, 39 mounted thereon which mesh respectively with gears 32 and 38 of shaft 24. A second driven shaft 46 which is also in axial alignment with shaft 24, has one end rotatably mounted in bearing 48 of plate 6 and the other end rotatably mounted in bearing 59 of plate 8. Shaft 46 has a pair of gears 31 and 37 mounted thereon which mesh respectively with gears 30 and 36. The operation of the cams and gears is as follows: When input shaft 24 is driven by a clutchbrake system (not shown), gear 38 drivingly meshes with gear 39. The rotation of gear 39 and shaft 40.causes rotation of gear 33 which in turn drivingly meshes with gear 32. The rotation of gear 32 causes rotation of sleeve 28, medium cam 25 and gear 30. Gear Si) in turn drivingly meshes with gear 31 mounted on shaft 46. Gear 37, which rotates with shaft 46, drivingly meshes with gear 36 and causes rotation of sleeve 34 and coarse cam member 27.

Referring to FIGURE 3 cam members 25, 26 and 27 are shown in engagement -with a roller 5 which is rotatably mounted on a stud 54. Stud 54 is secured in any suitable manner between members 56 and 58 which extend at ri ht angles and are integral with pivotal arm 18. Each of the cams has a groove on the periphery and at the beginning of each time interval the centers of these grooves are axially aligned beneath roller 5. The grooves as Well as the diameters of the cam members vary in size. in one particular embodiment of the invention the diameter of the fine cam member is equal to one inch while the groove has a depth of .040 inch and extends over an arc of The medium cam memarias-a her has a diameter which is .010 inch smaller than the fine cam, while the groove has a depth of .060 inch and extends over an arc of 16. The coarse cam member has a diameter which is .010 inch greater than the fine cam member while the groove has a depth of .062 inch and extends over an arc of 12. At the beginning of the interval timing operation the grooves of cams 25, 26 and 27 are axially aligned beneath roller 5 and due to the depth of the grooves the roller is not in contact with any of the cam members. When drive is applied to the input shaft the rotation of the fine cam will actuate the pivot arm which in turn overcomes the force exerted by a spring 60 and closes micro-switch '7 to start the timing cycle. The fine cam will always make 39.750 revolutions regardless of the length of the time interval. After fine cam 26 makes an initial three-quarters of a revolution in contact with roller 5, the medium cam then engages the roller for one-quarter of a revolution as measured by the fine cam. The fine cam then engages the roller again for a quarter of a revolution after which the coarse cam 27 engages the roller. Due to the larger diameter of cam 27, this cam remains in contact until the fine cam has completed thirty-nine revolutions. The roller then engages cam 26 for the final three-quarters of a revolution to end the cycle. During the timing interval while fine cam 26 makes 39.750 revolutions, the medium cam completes four revolutions and the coarse cam only one revolution. The different angular speeds of the cam members are due to the size and ratio of the gears used in the timing assembly. Once the input speed to the switch actuator is constant the time interval will remain fixed. To change the time interval the external gearing must be change so as to change the speed of the input shaft to the switch actuator. The accuracy of the switch actuator is directly related to the speed of the input shaft. The faster the input speed or shorter the time cycle the more accurate the time interval. In testing the accuracy of the interval switch actuator it was found that for a time interval of en seconds the accuracy was within .004 second. A forty second time interval was less accurate being within .010 second.

Referring to FIGURE 4 micro-switch '7 is shown in the actuated position during a time interval. The end of pivotal arm 18, which extends through the cut-away portion of plate 10, is yoke-shaped (see FIGURE 3) and has a threaded stud 52 passing through the center of the yoke. A screw 53 extends through arm 18 in a direction normal to stud 52 and applies compression to the yoke ends of pivotal arm 18 to provide a means for locking screw 53 in a desired position. A resilient member such as spring 60 is secured to micro-switch 7 by screws 59 and exerts a continual force on pivotal arm 18 through contact with the bottom of stud 52. When the timing cycle ends and the grooves on the cams are axially aligned, spring 60 causes a pivotal movement to arm 18 and roller 5 drops into the grooves. At the same time spring 60 breaks contact with a movable contact 62 thereby de-energizing micro-switch 7. The force exerted by spring 60 on stud 52 may be varied by raising or lowering stud 52. Screws 64, 66 extend through plate 10 and secure the yoke end of housing 20 to plate 10.

While we have shown and described a preferred embodiment of our invention, other modifications thereof Will readily occur to those skilled in the art and we therefore intend our invention to be limited only by the following claims.

The following invention is claimed:

1. A switch actuator having an output lever disposed for pivotal movement at predetermined time intervals comprrsmg:

(a) a cylindrical housing containing an input drive shaft rotatably mounted therein;

(b) a first and second sleeve member freely mounted on said input shaft for relative rotation thereto;

(0) a first and second cam member respectively secured to said first and second sleeve and disposed for rotation therewith;

(d) a third cam member mounted on said shaft intermediate said first and second cam members, said third cam member disposed for rotation by said input shaft;

(e) each of said cam members provided with portions which are in alignment at the beginning and end of a time interval, said portions engaging a lever overlying said cams and engageable therewith for pivotal movement thereof responsive to the alignment of said portions;

(1) drive means driven by said input drive shaft for rotating said first and second sleeve and cam members at difierent speeds for alignment of said portions at the predetermined time interval.

2. An actuator as set forth in claim 1 including:

(a) a pair of gears mounted on said first sleeve member, and;

(b) a single gear mounted on said second sleeve member,

(c) said pair of gears and said single gear disposed for rotation at different speeds by said drive means for the rotation of said sleeves and cam members relative to said input shaft.

3. An actuator as in claim 2 wherein said drive means includes:

(a) a gear mounted on one end of said input shaft;

(b) a first and second driven shaft;

(0) a first gear secured to said first driven shaft for meshing relationship with said input shaft gear for rotation thereby;

(d) a second gear mounted on said first driven shaft for meshing relationship with one of said gears on said first sleeve for rotation of said first sleeve and cam member relative to said input shaft;

(e) a first gear secured to said second driven shaft for meshing relationship with the other of said gears of said first sleeve for rotation thereby;

(f) a second gear secured to said second driven shaft for meshing relationship with said gear of said second sleeve for rotation of said second sleeve and cam member relative to said input shaft.

4. An actuator as in claim 3 wherein:

(a) said first, second and third cam members are respectively, a fine cam, a medium cam and a coarse cam;

(b) said portion of each of said cams being a groove disposed on the periphery of each of said cam members for simultaneous engagement with the lever responsive to alignment of said grooves.

5. A switch actuator having a pivoted output lever disposed for reciprocal movement at upper and lower positions at predetermined time intervals comprising:

(a) an outer cylinder having an open end and a closed end;

([1) an inner, central, and outer cylindrical plate secured to said cylinder;

(0) stud means attached to said plates whereby said plates are disposed in fixed parallel spaced relationship;

(d) each of said inner and central plates having a cutaway portion on the periphery thereof for housing the output lever;

(e) an input drive shaft extending through said outer plate and terminating between said inner and central plate;

(7) a first driven shaft having one end rotatably secured in said outer plate and the other end terminating between said inner and outer plates, and being disposed in axial alignment with said input drive shaft;

(g) a second driven shaft having one end rotatably secured in said outer plate and the other end rotatably secured in said central plate;

(It) said input drive shaft having a fine cam member and a first gear fixedly mounted thereon and a first and second sleeve freely mounted thereon;

(i) said first sleeve having a pair of gears and a medium cam member mounted thereon;

(j) said second sleeve having a gear and a coarse cam member mounted thereon;

(k) said medium, fine and coarse cam members being respectively disposed in close parallel relationship and said fine cam member having a diameter slightly less than said coarse cam member and slightly greater than said medium cam member;

(I) said first driven shaft having a first and second gear mounted thereon being disposed in axial alignment with said second driven shaft which has a first and second gear mounted thereon;

(in) the first gear of said input shaft meshing with the first gear of said first driven shaft;

(12) the second gear of said first driven shaft meshing with one of the gears on said first sleeve whereby said medium cam member is driven at one tenth the speed of said fine cam member;

(0) the other of said gears on said first sleeve meshing with the first gear of said second driven shaft;

(p) the second gear of said second driven shaft meshing with the gear on said second sleeve whereby said coarse cam member is driven at one-fortieth the speed of said fine cam member;

(q) each of said cam members being cylindrical and having a groove on the outer periphery thereof;

(1') said grooves being axially ali ned at the beginning and end of each timing interval, the length of said timing interval being directly proportional to the rotational speed of said input shaft;

(s) a roller attached to one end of the lever for engagement with said grooves at the beginning and end of each time interval for retention of the other end of said lever at the upper position;

(t) at least one of said cam members engaging said roller during the timing interval for retention of said other end of the lever in the lower position during the timing interval; and

(It) said fine cam member disposed for thirt -nine and three-quarters revolutions during said timing interval.

References Cited in the file of this patent UNITED STATES PATENTS 2,675,710 Ruhland Apr. 20, 1954 2,956,437 Opochensky Oct. 18, 1960 3,034,563 Fischer Apr. 9, 1963 

1. A SWITCH ACTUATOR HAVING AN OUTPUT LEVER DISPOSED FOR PIVOTAL MOVEMENT AT PREDETERMINED TIME INTERVALS COMPRISING: (A) A CYLINDRICAL HOUSING CONTAINING AN INPUT DRIVE SHAFT ROTATABLY MOUNTED THEREIN; (B) A FIRST AND SECOND SLEEVE MEMBER FREELY MOUNTED ON SAID INPUT SHAFT FOR RELATIVE ROTATION THERETO; (C) A FIRST AND SECOND CAM MEMBER RESPECTIVELY SECURED TO SAID FIRST AND SECOND SLEEVE AND DISPOSED FOR ROTATION THEREWITH; (D) A THIRD CAM MEMBER MOUNTED ON SAID SHAFT INTERMEDIATE SAID FIRST AND SECOND CAM MEMBERS, SAID THIRD CAM MEMBER DISPOSED FOR ROTATION BY SAID INPUT SHAFT; 